Inhibitors of Enhancer of Zeste Homolog (EZH2) are promising drugs for the treatment of various cancers. See e.g., WO 2013/120104 and WO 2014/124418. Of particular importance due to their heightened activity for EZH2 are those inhibitors which, among other structural features, contain a chiral center between a substituted piperidinyl and indolyl moiety. See e.g., (R)—N-((4-methoxy-6-methyl-2-oxo-1,2-dihydropyridin-3-yl)methyl)-2-methyl-1-(1-(1-(2,2,2-trifluoroethyl)piperidin-4-yl)ethyl)-1H-indole-3-carboxamide described in U.S. Pat. No. 9,085,583. Economical and efficient means for preparing these stereoselective inhibitors are needed.